About using "GL_CLAMP_TO_EDGE" parameter

While I tried to pass "GL_CLAMP_TO_EDGE" parameter to "glTexParameter()", I got an error compiling message: "undeclared identifier". I got OpenGL installed by CD from the book "OpenGL SuperBible", and I thought it''s version 1.2. Could anyone figure out why I cannot use "GL_CLAMP_TO_EDGE"? By the way, I cannot find the downloadable OpenGL1.2 on www.opengl.org. Where can I got it? Thanks a lot